Determining the Degree of Dopaminergic Denervation Based on the Loss of Nigral Hyperintensity on SMWI in Parkinsonism

Abstract

BACKGROUND AND PURPOSE: Nigrostriatal dopaminergic function in patients with Parkinson disease can be assessed using 123 I-2b -carbomethoxy-3b -(4-iodophenyl)-N-(3-fluoropropyl)-nortropan dopamine transporter ( 123 I-FP-CIT) SPECT, and a good correlation has been demonstrated between nigral status on SWI and dopaminergic denervation on 123 I-FP-CIT SPECT. Here, we aim to correlate quantified dopamine transporter attenuation on 123 I-FP-CIT SPECT with nigrosome-1 status using susceptibility map-weighted imaging (SMWI). MATERIALS AND METHODS:Between May 2017 and January 2018, consecutive patients with idiopathic Parkinson disease (n ¼ 109) and control participants (n ¼ 29) who underwent 123 I-FP-CIT SPECT with concurrent 3T SWI were included. SMWI was generated from SWI. Two neuroradiologists evaluated nigral hyperintensity from nigrosome-1 on each side of the substantia nigra. Using consensus reading, we compared the 123 I-FP-CIT-specific binding ratio according to nigral hyperintensity status and the 123 I-FP-CIT specific binding ratio threshold to confirm the loss of nigral hyperintensity was determined using receiver operating characteristic curve analysis. RESULTS:The concordance rate between SMWI and 123 I-FP-CIT SPECT was 65.9%. The 123 I-FP-CIT-specific binding ratios in the striatum, caudate nucleus, and putamen were significantly lower when nigral hyperintensity in the ipsilateral substantia nigra was absent than when present (all, P , .001). The 123 I-FP-CIT-specific binding ratio threshold values for the determination of nigral hyperintensity loss were 2.56 in the striatum (area under the curve, 0.890), 3.07 in the caudate nucleus (0.830), and 2.36 in the putamen (0.887).CONCLUSIONS: Nigral hyperintensity on SMWI showed high positive predictive value and low negative predictive value with dopaminergic degeneration on 123 I-FP-CIT SPECT. In patients with Parkinson disease, the loss of nigral hyperintensity is prominent in patients with lower striatal specific binding ratios. ABBREVIATIONS: PD ¼ Parkinson disease; SBR ¼ specific binding ratio; SMWI ¼ susceptibility map-weighted imaging; SN ¼ substantia nigra; 123 I-FP-CIT ¼ 123 I-2[b ]-carbomethoxy-3[b ]-(4-iodophenyl)-N-(3-fluoropropyl)-nortropan dopamine transporter; MMSE ¼ Mini-Mental State Examination; MoCA ¼ Montreal Cognitive Asses; UPDRS ¼ Unified Parkinson's Disease Rating Scale; ROC ¼ receiver operating characteristic; AUC ¼ area under the curve

Dorsolateral Nigral Hyperintensity on 1.5 T Versus 3 T Susceptibility‐Weighted Magnetic Resonance Imaging in Neurodegenerative Parkinsonism

“…16 A direct comparison of SMWI to standard SWI in the assessment of DNH resulted in a superiority of SMWI in terms of a higher interobserver agreement, a higher concordance rate with 123 I-FP-CIT SPECT and a higher diagnostic performance for PD. 17 Therefore, our results and the findings of previous studies using more advanced SWI techniques [16][17][18][19] emphasize the importance of appropriate technical standards to ensure a sufficient diagnostic accuracy of DNH in neurodegenerative parkinsonism. Particularly important in imaging the SN are a sufficient spatial resolution, the slice thickness and the signal-to-noise-ratio (SNR).…”

Comparative Performance of Susceptibility Map-Weighted MRI According to the Acquisition Planes in the Diagnosis of Neurodegenerative Parkinsonism

“…Many previous studies have demonstrated the high diagnostic performance of SMwI in assessing nigral hyperintensity [ 8 12 16 17 18 ]. However, most previous studies were conducted with varying imaging protocols, and presented conflicting assumptions regarding the optimal imaging plane for assessing nigral hyperintensity [ 9 20 ].…”

“…Prior studies have shown the high diagnostic performances of both SWI and SMwI in determining the nigral hyperintensity in the substantia nigra [ 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 ]. However, these studies used heterogeneous study populations and imaging protocols, and discretionally chose different types of MR acquisition planes.…”

“…One recent pioneering study assessed the loss of nigral hyperintensity as a biomarker of IPD using a plane parallel to the splenium and genu lines of the corpus callosum [ 4 ]. Several studies have further implemented a plane perpendicular to the midbrain [ 8 12 19 ], whereas others adopted an anterior commissure-posterior commissure (AC-PC) plane as it is easy to conduct and shows little deviation in repeated trials [ 17 ]. However, in a recent meta-analysis, the perpendicular plane showed better diagnostic performance than the AC-PC plane, with a sensitivity of 0.94 (95% confidence interval [CI], 0.82–1.00) and a specificity of 0.98 (95% CI, 0.95–1.00) on the perpendicular plane and 0.76 (95% CI, 0.86–1.00) and a specifity of 0.95 (95% CI, 0.91–0.99) on the AC-PC plane.…”

Nigrosome 1 visibility and its association with nigrostriatal dopaminergic loss in Parkinson's disease

“…One recent 123 I‐FP‐CIT single photon emission computed tomography (SPECT) study reported a similar degree of dopamine denervation required for the loss of nigral hyperintensity on SMwI in PD patients [28]. The researchers enrolled patients with frontal gait disorder, essential tremor, and drug‐induced parkinsonism as the control group, while excluding idiopathic RBD patients who are considered to be at risk for developing PD, and did not show individual SBRs of the study subjects.…”